The long-term objective of this project is to examine physiologic mechanisms by which hormones maintain differentiated function in prostate cancer cells. In the current studies we will use parent cultures of AXC rat prostate cancer cells, which we have shown to be tumorigenic in AXC rats and to be hormone responsive, to isolate clonal cell lines of AXC rat prostate cancer. We will select clonal cell lines with a predicted high probability of hormonal sensitivity by quantitating cell content of phenotypic markers, androgen, estrogen, and prolactin receptors, which are thought to be required for hormonal sensitivity. We will determine tumorigenicity of selected clonal cell lines which are predicted to be androgen-responsive or androgen-insensitive by inoculation into male AXC rats. Tumorigenic clonal cell lines will be used to evaluate the consequence of androgen deprivation upon in vivo and in vitro proliferation of clonal AXC rat prostate cancer cells predicted to be either androgen-responsive or androgen-insensitive.